The present invention refers to an improved valve with a ball-shaped stopper. More particularly, the present invention provides a single-piece stopper coated with a sealing material.
Valves with ball-shaped stoppers are presently known in various forms, which are mainly differentiated by the fact that the valve body is in one or more parts. Although the present invention refers to valves having ball-shaped stoppers in general, included in this designation as well are similar valves, such as gate valves and the like with ball stoppers. The present invention provides particularly significant advantages in valves having a single piece body. A valve of this type was disclosed by Italian Patent No. 1,101,585. The body of this valve disclosed therein features a housing for the ball-shaped stopper, a fluid inlet connection, a fluid outlet connection, and a hollow neck portion to permit the insertion of the stopper into the housing. The disclosed valve is also designed to accept the control rod which is connected to the ball, a seal is formed between the housing and the control rod by a flexible ring. The latter is housed in a circumferential groove on the internal surface of the neck portion. A handle, lever or similar device is connected to the control rod to permit the opening and closing movements of the ball stopper to be performed. The housing of the stopper in the valve body is provided with two opposite seats for two gaskets, between which the ball stopper forms a seal. The seal which prevents fluid from escaping toward the outside is provided by an O-ring disposed in a seat formed in the control rod and in a sealing relationship with the internal surface of the neck portion. The ball stopper disclosed has a seat for retaining a part of the control rod, which is also connected to the activation handle or lever by a screw.
Therefore, known ball-stopper valves require a large number of components, a variety of processing steps and three sealing gaskets. To diminish the friction between the stopper and the gaskets, the stopper is typically manufactured with a high degree of precision on its outer surface and subsequently plated with chrome. Also, the assembly of such known valves requires a number of individual assembly steps, which cannot all be readily conducted in an automated fashion.
In known embodiments of valves with a multiple part valve housing an even higher number of components is necessary, as a result of which the expenditure of time both for construction and assembly is even greater than that for ball valves with a housing in a single piece.
Although providing an unobjectionable operation and good seals, ball valves of the type described above thus have the disadvantage of requiring a large number of components, numerous manufacturing steps and a complex assembly procedure requiring an equivalent amount of time. This necessarily results in relatively high production costs.